A police spokeswoman said the incident happened about 4am.
A Fire and Emergency New Zealand crew was originally called out because of concerns the truck might be hauling dangerous goods, but was stood down.
Traffic was down to one lane at the crash site at the intersection of Cluden Creek Rd and State Highway 8 until the truck and trailer unit was removed about noon.
An Owens Transport company spokesman was at the scene yesterday morning but refused to comment.
The police spokeswoman said a police investigation into the accident would likely follow.